Boyle, coached by Mark Regan, made three finals.
Individually, she made finals in the 400m and 800m freestyle and in the 4x200m freestyle relay, and was also a semifinalist in the 200m freestyle. She set new national records in all including a whopping 5s in the 800m.
Boyle had set lofty goals for yesterday's final but it proved too much for the weary swimmer.
"The championships have taken a lot out of me," she said.
"I've never raced at this intensity and competed in so many heats, semifinals and finals and right now I am absolutely exhausted.
"I pushed out harder to give myself a chance and then I couldn't pull it together in the end.
"But I'm not beating myself up about it though. I gave it all I could."
Earlier, backstroker Daniel Bell could not advance in the heats of the 50m backstroke, finishing 22nd fastest in 25.91s.
The women's 800m freestyle was won by Rebecca Adlington (Britain) in 8:17.51, second Lotte Friis (Norway) 8:18.20 and third Kate Ziegler (US) 8:23.36.
- NZPA